Picosecond flash photolysis and spectroscopy: Bis-(4-dimethylaminodithiobenzil)-Ni(II), BDN

• Published in: Chemical physics letters 1974-09, Vol.28 (2), p.263-269
• Main Authors: Magde, Douglas, Bushaw, Bruce A., Windsor, Maurice W.
• Format: Article
• Language: English
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/0009-2614(74)80069-2

The transient absorption spectrum of an electronically excited dithiene, bis-(4-dimethylaminodithiobenzil)-Ni(II), which we term BDN, was measured with 10 ps temporal resolution and 1 nm wavelength resolution. For a series of “heavy atom” solvents, both the ground state and the excited state spectra remained constant while the decay kinetics of the excited state absorption, as well as the recovery from ground state bleaching, varied; the extreme values were 9 ns in benzene and 0.22 ns in iodoethane. The excited state spectrum can be plausibly fitted by a particular one electron transition between previously calculated molecular orbitals, although this clearly does not prove that these orbitals provide the best description for the excited states. Similarly, present data do not determine a unique decay scheme. We comment on three possibilities within the framework of the ground state virtual orbital picture. We are aware of no previous direct detection of excited states of such nickel complexes either in absorption or in emission. We conclude that our recently developed techniques will be generally applicable in probing the photodynamics of presently intractable molecular species. The significance of our data for laser mode-locking is discussed.